Over half of the world population is at risk for infection by dengue virus, a mosquito borne member of the Flavivirus family that consists of four distinct serotypes. Approximately 50 to 100 million infections occur annually resulting in an estimated 500,000 cases of life threatening dengue hemorrhagic fever or dengue shock syndrome. Due to the increased incidence and spreading geographic distribution of dengue infection, it is considered to be an emerging disease and is identified by NIAID as a category A priority pathogen. Despite the significant disease burden associated with dengue infection there is presently no approved vaccine or antiviral drug. The goal of this project is to discover and develop antiviral drugs that inhibit dengue virus infection by blocking the proteolytic activity of the dengue virus NS3 protein. The protease is a key enzyme in viral maturation and inhibition of flavivirus protease has been shown to dramatically reduce viral replication. Structure based drug design will provide a rapid path to potent and virus specific protease inhibitors. We will virtually screen the active site with a chemical library. These targets will be examined by molecular modeling through a process of virtual drug screening to find potential inhibitor compounds that will then be tested experimentally in vitro utilizing biochemical assays optimized during the course of the project. A cell based assay will also be used to confirm virus inhibition in a slightly more physiological environment. Compounds that are active versus the Dengue NS3 proteinase of serotype 2 will also be tested versus the other 3 serotypes, in order to identify potential broad spectrum dengue antiviral therapeutics. At the conclusion of Phase I we intend to select at least one lead series with high potency to be optimized toward producing an effective broad spectrum dengue antiviral drug and possible other Flaviviruses during Phase II. PUBLIC HEALTH RELEVANCE: Dengue fever causes more illness and death than any other arboviral disease and is spreading into new geographic areas, with 925,000 cases reported in 2006. No commercial prophylactic or therapeutic is available to treat the disease. Our strategy is to discover and optimize orally available antiviral drugs to prevent and treat Dengue virus infections, with potential broad spectrum activity versus all flaviviruses.